#define _CRT_SECURE_NO_WARNINGS 1
/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
 /**

class Solution {
public:
    void dfs(TreeNode* root, vector<int>& ret)
    {
        if (root == nullptr) return;
        dfs(root->left, ret);
        ret.emplace_back(root->val);
        dfs(root->right, ret);

    }

    vector<int> inorderTraversal(TreeNode* root)
    {
        vector<int>ret;
        dfs(root, ret);
        return ret;
    }
};

*/